It is believed that contemporary fuel injectors are designed to accommodate a particular engine. The ability to meet stringent tailpipe emission standards for mass-produced automotive vehicles is at least in part attributable to the ability to assure consistency in both shaping and aiming the injection spray or stream, e.g., toward an intake valve (or valves) or into a combustion cylinder. Wall wetting should be avoided.
Because of the large number of different engine models that use multi-point fuel injectors, a large number of unique injectors are needed to provide the desired shaping and aiming of the injection spray or stream for each cylinder of an engine. To accommodate these demands, fuel injectors have heretofore been designed to produce straight streams, bent streams, split streams, and split/bent streams. In fuel injectors utilizing thin disc orifice members, such injection patterns can be created solely by the specific design of the thin disc orifice member. This capability offers the opportunity for meaningful manufacturing economies since other components of the fuel injector are not necessarily required to have a unique design for a particular application, i.e. many other components can be of common design.
It is believed that known orifices can be formed in the following manner. A flat metering disc is formed with an orifice that extends generally perpendicular to the flat metering orifice disc, i.e., a “straight” orifice. In order to achieve a bending or split angle, i.e., an angle at which the orifice is oriented relative to a longitudinal axis of the fuel injector, the orifice can be formed by punching at an oblique angle relative to the longitudinal axis to provide an “angled orifice,” i.e., an orifice angled with respect to the planar surface of the metering disc or a longitudinal axis extending perpendicularly between the flat surfaces of the disc.
It is believed that a known punch tool is formed of carbide and has a cylindrical body extending along a tool axis with a generally planar surface at a working end of the punch tool. The tool axis can be oriented at an angle oblique to the tool axis and a punching force can be applied to the punch along the tool axis so that the punch can penetrate through a blank workpiece. While the punch tool has acceptable performance during the punching of straight wall orifices, the punch tool has been observed to provide a less than desirable performance when the punch tool is used to form angled orifices. In particular, the generally planar surface at the working end of the tool tends to break during the punching process. Even if the punch tool does not break during the angled orifice punching process, the punch tool may skip, slide, or deflect upon impact with the surface of the workpiece and therefore could cause the workpiece to be damaged and discarded. Further, the skipping, sliding, or deflecting of the punch could cause the workpiece to move around laterally or vertically. To avoid the movements of the workpiece, a complex workpiece retention arrangement is utilized to ensure that the workpiece is stationary relative to a support surface.
Therefore, it would be desirable to provide for a punch tool that would have greater durability during the punching process for an angled orifice without resorting to complex or costly attempts in maintaining the same tool design or die design. Such attempts may include manufacturing the tool using exotic metals or an elaborate alignment and retention jig. It would also be desirable to provide for a punch tool that avoids skipping, sliding, or deflecting of the known punch tool during impact with a blank work strip.